Multi-lead ECG course for Taney County Ambulance District.

1. Multi-lead
ECG

2. Goals
▪ Improve patient outcomes by reducing time from
first medical contact to PCI.
▪ Improve protocol compliance.
▪ Improve ECG interpretation skills of ALS
providers.

3. Objectives
▪ Describe the difference between monitoring and
assessing.
▪ Describe the importance of early ECG acquisition
and transmission.
▪ Demonstrate proper lead placement for a 12-
and 15-lead ECG.
▪ Describe a systematic approach of 12-lead
interpretation.

4. Monitoring vs Assessing
Monitoring
▪ The purpose of “monitoring”
is to identify any changes in
the patient’s heart rhythm.
▪ Does not diagnose!
▪ Lead placement doesn’t
matter.
▪ Stick one on the nose and
one on the toes…. V-Fib and
asystole will look the same.
Assessing
▪ Evaluating electrical
changes in a multi-lead
ECG.
▪ Identifying useful and
potentially life-saving
information.
▪ Utilizing this information
to prepare your treatment
plan
▪ Proper lead placement is
absolutely crucial!

5. Obtaining quality tracings

6. Obtaining quality tracings
▪ Prepare the skin
▪ Clean and dry the skin
▪ Shave any excessive hair
▪ Gently scrape skin to remove surface layer of dead
cells
▪ Position the patient
▪ Supine is best. Fowler’s or semi-fowlers is
acceptable.
▪ Serial ECG’s should be in same position.
▪ Place limbs on supportive surfaces
▪ Patient should be comfortable and relaxed.

7. Obtaining quality tracings cont…
▪ Stop the vehicle
▪ Secure the trunk cable to the patient’s clothing
▪ Position cables and/or lead wires to prevent
pulling away from the patient
▪ Ensure the electrodes are not dried out
Most poor tracings are the result of poor electrode-
skin contact and can be resolved with proper skin
preparation.

8. Lead
placement
does matter!

9. Lead Placement
▪ Limb leads
▪ RA/LA on forearm
proximal to wrist
▪ RL/LL on lower leg
proximal to ankle
▪ Avoid boney prominences
and major muscle groups
▪ Precordial leads
▪ V1 – 4th intercostal space
right of the sternum
▪ V2 – 4th intercostal space
left of the sternum
▪ V3 – Directly between
V2/V4
▪ V4 – 5th intercostal space
at midclavicular line
▪ V5 – Level with V4 at left
anterior axillary line
▪ V6 – Level with V5 at left
midaxillary line
(V4, V5, and V6 should be in
a straight line)

10. Locating V1
▪ Place your finger at the
notch in the top of the
sternum.
▪ Move your finger slowly
downward about 1.5 inches
to the Angle of Louis.
▪ Move lateral and just below
the Angle of Louis to the 2nd
intercostal space.
▪ Move your finger down two
more intercostal spaces to
the 4th intercostal space.

11. The Basics

12. P Waves
▪ P Wave:
▪ The first positive deflection from the
isoelectric line
▪ Represents Atrial depolarization
▪ Normal P wave morphology:
▪ Smooth contour
▪ Monophasic in lead II
▪ Biphasic in V1
▪ Normal P wave axis is between 0° and +75°
▪ P waves should be upright in leads I and II,
inverted in aVR
▪ < 120 ms (duration)
▪ < 2.5 mm in the limb leads (amplitude)
▪ < 1.5 mm in the precordial leads (amplitude)

13. Q Waves
▪ Q Wave:
▪ The first negative deflection from the
isoelectric line
▪ Represents the normal left-to-right
depolarization of the interventricular
septum
▪ Small ‘septal’ Q waves are typically seen in
the left-sided leads (I, aVL, V5 and V6)
▪ Small Q waves are normal in most leads
▪ Deeper Q waves (>2 mm) may be seen in
leads III and aVR as a normal variant
▪ Under normal circumstances, Q waves are
not seen in the right-sided leads (V1-3)
▪ Considered pathological if:
▪ > 40 ms (1 mm) wide
▪ > 2 mm deep
▪ > 25% of depth of QRS complex
▪ Seen in leads V1-3

14. Other Waves
▪ R Wave:
▪ The first positive deflection from the
isoelectric line
▪ S Wave:
▪ The first negative deflection from the
isoelectric line after the R wave
▪ R Prime Wave:
▪ The second positive deflection in a QRS
complex
▪ QS Wave:
▪ The entire complex is negative (there is
no R wave to help identify the Q or S
wave)
▪ Delta Wave:
▪ A slurred upstroke in the QRS complex

15. WOLFF-PARKINSON-WHITE SYNDROME

16. Systematic
Approach
To 12-Lead ECG Interpretation

17. Systematic Approach
▪ Identify the underlying Rhythm (Lead II)
▪ In wide-complex tachycardia use the VT criteria
▪ Evaluate the Axis for deviation and hemiblocks
▪ Determine the presence of a Bundle Branch
Block (BBB)
▪ Using ISAL, determine infract location.
▪ Secondary Survey

18. Identifying VT
▪ 12-lead ECG is 96% diagnostic for VT
identification.
▪ Lead II is only 34% accurate for diagnosing VT.
▪ A-fib with WPW and SVT with BBB are often
misdiagnosed as VT.

19. VT using axis criteria
▪ ERAD w/positive
deflection in V1 = VT
▪ Upright V1 is one of three
criteria
▪ Big mountain, little
mountain
▪ Steep peek (“steeple”)
▪ Slurred downstroke
(fireman’s hat)
▪ RAD w/negative
deflection in V1 = VT
▪ Fat R wave (>40ms)
▪ Notched or slurred
downstroke
▪ Pathological LAD
w/positive V1
▪ In patients with previous
MI

20. Other VT indicators/criteria
▪ Concordance in precordial leads.
▪ Negative concordance suggests VT. Be sure to
determine if the rhythm is atrial in origin. A LBBB
can be negative concordance.
▪ Positive concordance may indicate either VT or
WPW. Must rule out WPW before determining VT.
▪ AV dissociation
▪ Cannon A waves
▪ P waves out of place
▪ Different S1 heart sound

21. VT?

22. VT?

23. Axis and Hemiblocks
▪ The Axis is the
direction of flow of
the electrical
impulses.

24. Axis and Hemibocks

25. Axis Deviation Causes
▪ Left Axis Deviation
▪ Normal variation
▪ Mechanical shifts from
expiration, ascites,
abdominal tumors, high
diaphragm from
pregnancy, obesity, etc.
▪ Left anterior hemiblock
▪ LBBB
▪ WPW syndrome
▪ Hyperkalemia
▪ Right Axis Deviation
▪ Mechanical shifts from
inspiration, emphysema
▪ RVH
▪ RBBB
▪ Left posterior hemiblock
▪ WPW syndrome
▪ Pulmonary embolism
▪ Arrhythmias

26. Axis and Hemibock Chart
Axis Lead I Lead II Lead III Notes
Normal Axis
0° to 90°
Physiological Left Axis
0° to -40°
Pathological Left Axis
-40° to -90°
Anterior
Hemiblock
Right Axis
90° to 180°
Posterior
Hemiblock
Extreme Right Axis
>180°
Ventricular in
origin

27. Bundle Branch Blocks
▪ Two types
▪ LBBB
▪ RBBB
▪ Diagnosed in lead
V1
▪ QRS complex width
>120 ms (0.12 sec)
▪ Use the Turn signal
approach

28. Bundle Branch Blocks

29. Bundle Branch Blocks

30. Bifascicular blocks
▪ A bifascicular block is a
blockage of two of the
three pathways to
contract the ventricles in
an organized fashion.
▪ A LBBB is always a
bifascicular block.
▪ An anterior or posterior
hemiblock with a RBBB is
also a bifascicular block

31. Trifascicular blocks
Combination RBB LAD LPD ECG
1 C C C Complete AVB
2 C C I RBBB + LAH + AVB
3 C I C RBBB + LPH + AVB
4 I C C LBBB + AVB
5 C I I
Various combinations depending
upon relative degrees of
incomplete fascicular block
6 I C I
7 I I C
8 I I I
** C = completely blocked, I = incompletely blocked, and AVB = manifestations
of first or second degree A-V block

32. I See All Leads

33. ST Changes
▪ Measure for ST changes
1 mm past the J-point
(40 ms)
▪ Must be >1 mm to be
significant
▪ Must occur in two or
more contiguous or
continuous leads

34. ST Changes

35. Ischemia, Injury, and Infarction
▪ Ischemia – lack of oxygen
▪ Represented by T-wave inversion
▪ Increased T-wave amplitude
▪ ST-segment depression
▪ Injury – “Acute MI”
▪ Represented by ST-segment elevation
▪ Infarction – Necrosis/dead
▪ Represented by pathological Q-waves
▪ Q-wave is wider than .04 sec
▪ Q-wave is greater than 1/3 the entire QRS complex

36. AMI Locator
• Inferior = RCA
• Leads II, III, aVF
• Reciprical I, aVL
• Septal = LAD
• Leads V1, V2
• Anterior = LAD

37. Coronary Blood Supply

38. What to expect
▪ Anterior MI – LAD
▪ Most lethal, highest mortality. “Widow Maker”
▪ Can develop Complete Heart Block, VF, or VT
▪ If presents with hemiblocks or BBB; apply combo
pads and prepare for the worst
▪ Can extend into the septum and/or lateral walls
▪ Nitrates are great!
▪ Spare the fluids

39. What to expect
▪ Inferior MI - RCA
▪ Most common seen
▪ Can be very lethal
▪ 50% have posterior and/or right ventricle
involvement and hypotension
▪ Could also have 1st degree AV block or 2nd degree
type 1 AV block
▪ Nausea is common
▪ Look for RVI with V4R
▪ Nitrates with caution
▪ Fluids may be needed to support BP

40. 15-lead ECG
▪ Can locate isolated posterior MI
▪ ST segment depression in V1 is good indicator
(reciprocal changes)
▪ Use V8 and V9 and V4R
▪ Should be done on all Inferior MI to look for Right
Ventricular infarction.
▪ 50% of Inferior MI have posterior and/or right
ventricle involvement
▪ RVI is a preload problem and could cause dramatic
hypotension with nitrates.
▪ Clinical signs of RVI include JVD, dry lungs, and
hypotension

41. 15-Lead ECG
• V4R – 5th intercostal space
midclavicular line (same as V4
but on the other side)
• V8 – On the back, 5th
intercostal space midscapular
line.
• V9 – On the back, 5th
intercostal space between V8
and the spine.
• Move V4 to V4R
• Move V5 to V8
• Move V6 to V9
• Run a second ECG
• Label the different leads.

42. 15-lead ECG

43. LBBB…now what? Think QRS
▪ Q waves seen in at least two lateral leads (I, aVL, V5, V6)
▪ R wave regression seen from leads V1-V4
▪ Late notching of the S wave in at least 2 of leads V3-V5
I aVL V5 V6
V1 V2 V3 V4

44. AMI in LBBB
▪ Gusto-1 trial
▪ Look for three things
▪ Is there ST-segment elevation >=1mm and is concordant
with QRS axis?
▪ Is there ST-segment depression >=1mm in V1, V2, or V3?

45. AMI in LBBB cont…
▪ Is there ST-segment elevation >=5mm discordant from the
QRS axis?
▪ Yes to two or more of these questions shows a greater than 90%
chance the patient is having an AMI.

46. Atrial Abnormalities
▪ Right Atrial Enlargement (RAE)
▪ Tall, Pointed P waves in Inferior leads >2.5mm
▪ Think 3 P’s… Pointed, Prominent, Pulmonary
▪ Causes of RAE
▪ Congenital heart disease
▪ Tricuspid or pulmonary valve disease
▪ Pulmonary hypertension
▪ Implications:
▪ Generally not an acute problem
▪ Frequently seen with Right Ventricular Hypertophy
▪ Can be seen with other criteria indicating more severe
problems, i.e. pulmonary embolism

47. Atrial Abnormalities
▪ Left Atrial Enlargement (LAE)
▪ Lead II: widened P wave with a
notched or “m” shaped appearance
▪ Lead V1: broad, terminal negative P
deflection of more than 1 mm.
▪ Causes of LAE
▪ Hypertension
▪ Pulmonary edema
▪ LVH
▪ AMI
▪ Mitral or aortic valve stenosis
▪ Implications
▪ See causes… no treatment of the
specific problem.

48. Ventricular Hypertrophy
▪ Right Ventricular Hypertophy
▪ Caused by increased pressure in the right ventricle
▪ ECG findings:
▪ RAE
▪ Narrow QRS
▪ Right Axis Deviation
▪ R wave height in V1 >7mm
▪ Asymmetrical downsloping ST segment in inferior
leads. “Strain”
▪ Implications:
▪ Not an acute problem
▪ Similar causes as RAE

49. Right Ventricular Hypertrophy

50. Ventricular Hypertrophy
▪ Left Ventricular Hypertrophy (LVH)
▪ Caused by increased pressure or volume in the left
ventricle.
▪ Often found in:
▪ HTN
▪ AMI
▪ Ischemic heart disease
▪ Cardiomyopathy
▪ ECG Criteria:
▪ LAE (this plus any other QRS voltage criteria is diagnostic)
▪ QRS is generally narrow or slightly widened with “strain”
▪ Axis is usually normal

51. Ventricular Hypertrophy
▪ Left Ventricular Hypertrophy (LVH) cont…
▪ Voltage Criteria:
▪ Rule of 35
▪ Measure the deepest S wave from either V1 or V2; add this
number to the tallest R wave of lead V5 or V6. If this
number is greater than 35, and the patient is at least 35
years old, then criteria is met.
▪ R wave in Lead aVL is >11mm
▪ R wave >20 mm in inferior leads
▪ R wave >20 mm in V6
▪ R wave >25 mm in V5
▪ S wave > 25 mm in V1 or V2
▪ If complexes look large, assume hypertrophy. Look
for evidence of “strain”

52. “Strain”
▪ Strain is the hallmark presentation of
hypertrophy.
▪ A strain pattern is to hypertrophy what reciprocal
changes are to ST elevation; they clinch the
diagnosis.
▪ Strain is evidenced by asymmetrical ST
depression and T wave inversion that almost
looks biphasic.
▪ Best seen in lateral or inferior leads. (II, III, aVF,
V5, or V6)

53. “Strain”

54. Ventricular Hypertrophy
▪ Concerns with LVH
▪ Patients with LVH have a higher incidence of
sudden death and ischemic arrhythmias
▪ It can mimic the ST depression or elevation seen
with myocardial ischemia
▪ It may be caused by AMI
▪ In the presence of LBBB, LVH criteria are not
determined
▪ May be a useful clue as to hemodynamic condition

55. Electrolyte Disturbances
▪ Potassium (K+)
▪ Hypokalemia
▪ Serum levels below 3.5-5 mEq/L
▪ Common causes include vomiting, diarrhea, and diuretics
▪ Common signs and symptoms include
▪ Muscle weakness
▪ Polyuria
▪ Atrial flutter, heart blocks and bradycardia
▪ ECG findings
▪ ST segment depression
▪ T waves flattened or joined with U waves
▪ U waves get larger than T wave as potassium drops
▪ QT interval appears to lengthen
▪ PR interval increases

56. Electrolyte Disturbances
▪ Hypokalemia

57. Electrolyte Disturbances
▪ Potassium (K+)
▪ Hypokalemia treatment
▪ Monitor ECG
▪ Increase dietary intake of potassium
▪ In severe cases, IV KCL

58. Electrolyte Disturbances
▪ Potassium (K+)
▪ Hyperkalemia
▪ Serum levels above the normal range (3.5 – 5.0
mEq/L)
▪ Most commonly caused by renal failure
▪ SA node can quit at 7.5 mEq/L
▪ VF or asystole at 10-12 mEq/L

59. Electrolyte Disturbances
▪ Potassium (K+)
▪ Hyperkalemia ECG findings
▪ Mild cases (<6.5 mEq/L)
▪ Tall tented “peaked” T waves with narrow base
▪ Normal P waves
▪ Best seen in leads II, III, V2 and V4
▪ Moderate cases (<8 mEq/L)
▪ QRS widens
▪ Broad S waves in V leads
▪ LAD
▪ ST segment is gone, contiguous with the peaked T waves
▪ P waves start to go away
▪ Severe cases (>8 mEq/L)
▪ P waves disappear
▪ Sine waves

60. Electrolyte Disturbances
▪ Potassium
(K+)

61. Electrolyte Disturbances
▪ Potassium (K+)
▪ Hyperkalemia Treatment
▪ Sodium Bicarb 100-150 mEq added to 1 Liter bag of NS
▪ Consider IV Calcium Gluconate 10% 10-30 ml IV over 1-5
minutes
▪ Consider Glucose 10% 200-500 ml in 30 minutes and
500-1000 ml over the next several hours

62. QT Interval
▪ QT interval represents the time from start of
depolarization of the ventricles to the end of
repolarization.
▪ Measured from the start of the QRS complex to the
end of the T wave.
▪ Causes of Prolonged QT interval include:
▪ Hypokalemia, Hypocalcemia
▪ Drugs: quinidine, amiodarone, tricyclics, disopyramide,
phenothiazines
▪ Liquid protein diets, myocarditis, AMI, LVH, hypothermia
▪ Causes of Shortened QT interval include;
▪ Hypercalcemia, Digitalis therapy

63. QT interval
QT Interval Table
Heart Rate R-R Interval QTc and Range
40 1500 460 (410-510)
50 1200 420 (380-460)
60 1000 390 (350-430)
70 860 370 (330-410)
80 750 350 (320-390)
90 670 330 (300-360)
100 600 310 (280-340)
120 500 290 (260-320)
150 400 250 (230-280)
180 330 230 (210-250)
200 300 220 (200-240)

64. Pericarditis
▪ S/S of Pericarditis
▪ Chest pain, dyspnea, tachycardia, FEVER, weakness
▪ CP can be sharp and severe
▪ Made worse by LYING Flat, better by SITTING UP
▪ Pain for hours or days
▪ 90% have ECG evidence
▪ ECG findings include:
▪ ST segment elevation
▪ Concave (curved up) in all leads except V1 and aVR
▪ T wave elevation (starts above the isoelectric line)
▪ ST segment depression or T wave inversion
▪ Almost all leads down (later stage)

65. Pericarditis
▪ Pericarditis diagnosis
▪ Chest pain, pleuritic, relieving factors
▪ No response to NTG
▪ Pericardial rub
▪ ECG changes do not localize an artery (everything up)

66. Putting it all together
Prep the patient (shave, dry, position, calm)
Place leads in proper places
Analyze ECG
Identify rhythm
If wide complex use VT criteria
Evaluate Axis and Hemiblocks
Evaluate QRS width in V1 for BBB
LBBB and AMI criteria
Evaluate for acute MI
ST segment changes
I see all leads
15 lead if necessary
Treat for Acute MI if present
Comprehensive assessment
Chamber enlargement
Electrolyte changes
QT interval
Other conditions

67. Transmitting
▪ Two types of transmitting
▪ From Archives
▪ From Home screen
▪ Two types of connections
▪ Direct Connect
▪ Bluetooth
▪ Two types of destinations
▪ To a receiving facility
▪ To a PCR

68. Transmitting
▪ To a Receiving Facility
▪ All 12-leads should be transmitted
▪ Generally done from the home screen
▪ Uses the Titan Gateway
▪ Procedure
▪ Obtain a quality ECG
▪ Ensure the Titan Gateway is plugged in
▪ Press Transmit button
▪ Select Report (ie. 12-Lead 1)
▪ Select Site (ie. SRMC Branson)
▪ Send

69. Titan Gateway
▪ Titan II Wireless Gateway
▪ Transmits data from the LP15 to
the LifeNet system
▪ Connects to the TCADMobile wifi
▪ Only works when plugged in
▪ Only works when in range of the
ambulance
▪ Is not a modem
▪ LifeNet system

70. Let’s Practice!

71. Let’s Practice!

72. Let’s Practice!

73. Let’s Practice!

74. Let’s Practice!

75. Let’s Practice!

76. Let’s Practice!

77. Let’s Practice!

78. Let’s Practice!

79. Let’s Practice!

80. Let’s Practice!

81. References
▪ Conover, M. B. (1992). Understanding
Electrocardiography Arrhythmias and the 12-lead
ECG. St. Louis: Mosby Year Book.
▪ Marriott, H. J. (1988). Practical
Electrocardiography. Baltimore: Williams &
Wilkins.
▪ Page, R. (2005). 12-lead ECG for Acute and
Critical Care Providers. Upper Saddle River:
Pearson Education, Inc.
▪ Wellens, H. J., & Conover, M. B. (1992). The ECG
in Emergency Decision Making. Philadelphia:
W.B. Saunders Company.